Some 1,500 motorists are to be refunded and a toll operator is facing financial penalties after an overcharging incident, a Fine Gael TD has said.

Fine Gael TD and Chair of the Oireachtas Transport Committe, Fergus O'Dowd said customers' "trust will be hard won again" after 1,500 motorists were overcharged at the Drogheda toll plaza on the M1 motorway.

Celtic Roads Group, operator of the M1 motorway toll, has apologised after it emerged that some 1,500 drivers using the route between Gormanston, County Meath and Ballymascanian, County Louth were overcharged.

Electronic payment tag holders who left the motorway for less than three hours before resuming their journeys should not have been subject to a second charge on returning to the motorway,.

However, 1,500 customers were charged for 2,000 transactions accounting to €6,000 since last April.

In December, Mr O'Dowd raised concerns with toll operator Celtic Roads Group that motorists were paying over the odds for their journey.

Mr O'Dowd said there are "serious questions" to be answered and confirmed that Transport Infrastructure Ireland (TII) will be carrying out a full audit following his representations.

In a statement released today, Mr 'Dowd said that affected customers will get their money back but added that it is "not good enough".

Mr O'Dowd confirmed that Transport Infrastructure Ireland (TII) will carry out a full audit, following his representations.

He addedl “I also called for the toll operator- Celtic Roads Group – to face financial penalties for the issue, and TII has confirmed this will take place.“